Calcium difluoride single crystal with small scattering (sic), refractive index difference and number of small angle grain boundaries useful in the production of computer chips and electronic circuits

摘要

Process for preparation of a CaF 2single crystal of small scattering (sic), refractive index difference and number of small angle grain boundaries involving growth of the crystal from a CaF 2material melt by cooling the melt followed by tempering, where the CaF 2crystal raw material is vaporized at no less than 1,100[deg]C under a maximum vacuum of 5.10 -4and condensed at 500-1,280[deg]C to give a CaF 2melt which is converted to the gas phase for at least 5 hours and at 1,000-1,250[deg]C.